Problem with Stonington Blend grow

[Bekay]

You can see the details of the grow posted in Organic section or click here https://www.autoflower.org/threads/...and-tyrone-special-in-stonington-blend.48612/ everything has been coming along but I lowered the 400 watt HPS in a air-cooled reflector to 13 inches four days ago as was suggested in that thread. Also added some of the Stonington Blend Organic Plant Food, 5-2-4, as a topping and then cultivated the top 1/2 inch of soil and watered with pH 6.8. I don't know what is going on but I see some cupping of leaves, some brown spots and yellowing of lower leaves (earlier than expected - now day 47).
See what you think.

The plants are due a watering in tomorrow so there is an opportunity to feed or flush if desired. I did move the lamp up to 17 inches in the case that this is light burn. Temps have been between 62 F and 80 F; RH 25%-40%.
I looked at Wiara's deficiencies post https://www.autoflower.org/threads/quick-and-dirty-deficiency-picture-depot-expanded.43164/ and can't decide if this is P or K deficiency or something else. Any help would be appreciated.

 

[Waira]

Bekay- Time to get busy with the bloom nute's and supplements, no more N-favored nutrients at this stage!...especially the bloom booster,... otherwise, use the feed chart for Roots as a general guideline for what to use, and about how much,... always start with reduced conc. ( in Roots case, about 1/2 str.), until you see how they react to the goodies, then you can up conc. gradually,...
... I assume you're testing the soil pH using the run-off method? it's a dicey one, frankly, prone to several sources of measurement error...check this sticky article out for an improved methodology-> https://www.autoflower.org/threads/...-for-run-off-testing-and-ph-estimation.41733/ ...organics nutes or not, soil pH needs be checked often,... only the skilled TLO soil growers can let regular pH checks slide, IMHO,... The best way is direct measurement, of course, and the Accurate 8 soil pH probe is a good choice for the money,..works on the same principle as the skinny cheapie probes you see at garden centers, etc,... but much more robustly built and accurate! Consider scoring one- .... meantime, next chance you get, do that run-off test, and make sure your pH meter is calibrated,...
....looking at the leaf, the way the necrotic spots are hugging the main rib vein,... I'm not sure-- Ca defc. tends to do this, but not in such a big patch, but P defc. more atypically can, and given the lack of recent P (and K) inputs this far into blooming, I'm leaning toward those as the likely suspect; I do see some overall color fading here and there lower and upper leaves, which also might be part of the defc.'s, but a soil pH reading is needed to confirm you have a simple lack-of defc., not a pH lockout type instead,... the curling, most likely the light being too close (heat + intensity), combined with the low RH,...

 

[Bekay]

Thanks Waira, I will get on this and post in the grow log started in Organics. Cheers.

 

[Bekay]

Day #69 update.
@Waira, @Waximus - Just wanted to show you how things have come along ... details and harvesting question in original grow post here:
https://www.autoflower.org/threads/...rone-special-in-stonington-blend.48612/page-3
I got the MicroBlast and have been feeding 2x water 1x since Day #56. The sugar leaves are turning yellow but there are no amber trich's to be found. The girls look mistreated or just getting on?

Peace.